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Thread: How to pick a 400EX cam (a specification comparison)

  1. #21
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    Ryan
    2008 YFZ450 Gray/Red
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    2007 TRX400ex Sold http://nwmx.weebly.com/index.html
    HondaRidinRyan (youtube), commander1ryan (xbox live)

  2. #22
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    Cam?

    If anyone could help me i would sure appreicate it, i am looking for a cam for my 2000 400ex, i have a std bore je 12:1 comp piston in it, a full curtis sparks exhaust, stage 3 rev box, i am lookin for a cam that is mostly bottom end and mid range, i been lookin at the hotcams but they say mid to top range and im wanting bottom and mid, can some 1 please help me, any suggestions? Thanks

  3. #23
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    Re: Cam?

    Originally posted by Js7bla
    If anyone could help me i would sure appreicate it, i am looking for a cam for my 2000 400ex, i have a std bore je 12:1 comp piston in it, a full curtis sparks exhaust, stage 3 rev box, i am lookin for a cam that is mostly bottom end and mid range, i been lookin at the hotcams but they say mid to top range and im wanting bottom and mid, can some 1 please help me, any suggestions? Thanks
    what they mean by mid and top is added mid and top over the stock cam
    the best way to get an idea of how a camshaft will effect your motor is by looking at duration, typical added duration provides an earlier intake opening point and a later intake closing point therfore adding more duration (or time the valve is open) to the cam. BUT there are other factors that truely determan the power range the cam is going to work in. example: because i mostly build raptor 660's i will give an example of two cams that look identical based off lift and duration but will perform totaly different
    the X3 is a 276 intake duration and 274 exhaust duration
    the X4 is a 276 intake duration and 274 exhaust duration
    both cams have identical duration and lift but the X3 has and earlier intake opening point and and earlier intake closing point making up the 276 duration and the x4 has a later intake opening point and a later intake closing point
    X3 Intake open 36 BTDC Intake close 60 ABDC
    X4 intake open 30 BTDC intake close 66 ABDC
    so even though duration might be the same actualy performance of the cam and power range is based off of overall duration, intake closing point, LSA (lobe seperation angle), and overlap...so when comparing two cam like the X3 and X4 the different opening and closing points of the cam determain the total amount of duration, lsa, and overlap a cam has the
    X3 has more overlap and a tighter LSA
    where as the X4 has less overlap and a wider LSA so they will performe differently and are designed for two different engine profiles the X3 is more of a stroker style cam where as the X4 works better in a big bore high rpm engine
    anyways back to the 400ex and a list of duration and in general the given rpm range where the cam will make its best power
    210-220= 1000-5200rpm
    220-230= 1500-5700rpm
    230-240= 2000-6200rpm
    240-250= 2500-6700rpm
    250-260= 3000-7200rpm
    260-270= 3500-7700rpm
    270-280= 4000-8200rpm
    280-290= 4500-8700rpm
    typicaly for every 10 degrees duration you move the power band up 500 rpm but if you have a degreeable cam sprocket, taking any given cam and advancing/retarding the timing by 4 degrees will move the powerband up or down 300-400 rpm
    advancing the cam timing will move the powerband lower where as retarding the cam timing will move the powerband higher
    i would look into a stage two or even stage 3 hotcam for your set up, even a stage 3 with 262 duration falls into a solid midrange engine if you figure with your rev box adding rpm and being set at lets say 10500 rpm then a stage 3 cam is pretty well in the middle, also with a later intake closing point you will bleed off alittle more compression and you should be able to run high octane pump gas in that 12:1 engine, and odds are if you have 12:1 in your set up now with a stock cam, i would say your jetting is rich because you should be getting knock if you run it on pump gas, and if you run race gas i wouldnt run straight race gas (depending on what octane it is) you will be fine with about 98 octane so (like me) if you have 110 available at the pump, mix it 50/50 with 87 ctane this will take that 110 down to 98.5 octane and with the added lead in the 110 you should have no problem with heat in the motor...this is just my opinion based on the knowledge i have

  4. #24
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    Originally posted by GPracer2500
    I see a lot of discussion about the HC stage 2 vs. the HC stage 1 for a stock compression engine. I've done some calculations to define how much the stage 2 might hurt bottom end performance. If you read the entire first post then you know that the issue is the loss of compression from the intake valves staying open a long(er) time. Compression is a dominating factor for producing low end torque. Here's the difference:

    Taking into account the valve specifications:

    Stock cam cranking compression at 1000ft = 8.2:1
    HC stage 1 cranking compression at 1000ft = 7.8:1
    HC stage 2 cranking compression at 1000ft = 7.6:1

    If you go to a 11.0:1 piston (instead of the stock 9.1:1 piston) then the numbers change to:

    stock cam: 9.9:1
    HC stg 1: 9.5:1
    HC stg 2: 9.2:1

    (figures may not be absolute but the comparison is accurate)
    To me this says that the stock cam is better because don't you want higher compresion? Or with less compression you get higher top speed?
    Ryan
    2008 YFZ450 Gray/Red
    Pro Armor bumper
    Dr.D slip-on exhaust
    Twin Air Filter
    Blingstar sprocket and rotor guard
    ITP Quadcross XC rear tires on Tech 3 Hipers
    Black Outs!

    2007 TRX400ex Sold http://nwmx.weebly.com/index.html
    HondaRidinRyan (youtube), commander1ryan (xbox live)

  5. #25
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    i guess i really didnt get into static compression and dynamic compression

    compression is only one peice of the puzzle in building a big HP motor
    yes when you put in a bigger cam with a stock piston or any piston for that matter, the compression will drop with a bigger cam vs. a smaller cam
    this is known as static compression (if the intake valve closes at BDC), and dynamic compression (because the intake valve closes how many ever degrees after BDC based on the cam profile)
    BUT you have a window of peformance here, typicaly you do not want your dynamic compression to fall much below the 7.5:1 mark, some may argue with this compression ratio but once you hit that mark your cranking compression starts to fall beyond the usuable mark, this is why the higher compression piston is needed, im pretty sure i stated it before and i will state it again, just because you have a 12:1 piston in your engine does not mean you need to run high octane race fuel, but most do because they like to say they have to run it...blah blah, what they dont know is that they are losing power because the fuel actualy burns slower, and depending on the ignition curve they probably wont actualy burn as much in a cycle as what they would with a lower octane,
    as long as you stick to 200 give or take 10 psi on cranking compression you will be just fine on 93 octane, and higher and its time to start uping the octane rating but just because you cant run 93 doesnt mean you have to dedicate your engine to 110, start mixing the two and get a more usuable octane. and i will say this for everyone out there with a cam and high compression engine NONE of you need 110, 110 is stable for about 300 psi cranking which equates to arround 13.25 DYNAMIC compression so for any of you thinking you may be close well you would need 15:1 piston with a stock cam, so for all you running 110 really its not needed and you are wasting your money but just beware of your dynamic and cranking pressure
    back to the high compression low compression and rpms
    high compression will always make more power and torque across the board when compared to lower compression but typicaly you see the bigger gains made in the lower rpm range when you are "off" the cam, high compression will also always give more snap when tuned right over a lower compression piston
    some people do run the stage two cam with the stock piston which is ok, but you may not be happy with the results of going to this cam unless it is with an 11:1 or so piston to bring the dynamic compression back up
    well i hope i coverd a few more things for some people

  6. #26
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    nc
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    im just wondering with my setup 11.1 piston should i keep the stage 3 hotcam or get another cam i have plenty of bottom end power i mean plenty 1-3rd but i wouldnt mine having a little bit more on the top end what do u guys think.
    460ex stroker ,triple rate shocks w/reserves,cfm alum. airbox,denton racing steering stablelizer,big gun over rev rev box, uni filter,stage 3 hotcam,renthal handlebars,msr clutch,full skid plate, pro peg nerf bars,trail tech vapor,fst secondary oil cooler,+1mm kibble white black diamond valves,port and polish,custom seat,maxis razr2 lonestar racing bearing carrier,gt thunder hd studs,barnett clutches and etc 16/38 gearing.sparks 39mm fcr carb.sparks x-6 bigcore exhaust.next mod will be clutches and tires alottttttttttttttttttt of money spent ok new clutches are installed sparks 8-plate system.next tires or more suspension mods
    this ex is getting real expensive
    real quick.but its real fastttttttt
    new sidewinder smart chain 2 and t2 16tooth front sprocket.can u say lifetime warranty on the sprocket.$$$

  7. #27
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    Jan 2004
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    Layton, UT
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    400EX Cam Help?

    I have a Motor I took the cam out of and I am not sure if it is stock or not. It came out of a 440. I just am not sure if it is stock. There is some scribing on it. I think it is 81HT...but I am not sure. I tried to get PICs of the scribe but they won't come out. If you guys can help....thanks!!
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    Ride it like you borrowed it from your best friend!!

  8. #28
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    can you put a 450r cam in?
    ride it like you stole it

    2004 honda 400ex

    k&n air filter

    itp tires and rims all around

    works tripple rate shocks

    pro taper bars

    dyno jet kit... 165 main

    troy graphics kit

    stage 2 hot cam

    crf450 cam chain

    lexx pipe

  9. #29
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    Mar 2010
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    Findlay, ohio
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    Re: 400EX Cam Help?

    Originally posted by papasmurf660
    I have a Motor I took the cam out of and I am not sure if it is stock or not. It came out of a 440. I just am not sure if it is stock. There is some scribing on it. I think it is 81HT...but I am not sure. I tried to get PICs of the scribe but they won't come out. If you guys can help....thanks!!

    that is deflently not a stock cam... it doesnt have the compreshion release on it that comes on the stock cam... i cant say what it may be but i know it aint stock
    440ex/with JE 12.1 piston/old syle stage2 cam hot cam/port&polish ported head/hotrods crank/2degree timing key/no base gasket for beter deck height/k&n filter with flow kit/fmf power core4 shorty cut down 4in./powerbomb header/dynojet kit MJ185 pilot jet45/ 1/4inch intake spacer/ choke removed/16T 36T sprockets/dougless polished rims 22/6/10 fronts/ 20/10/9 rear holeshots/ tripple rate works front shocks

    build on the cheap
    2003 banshee.. 60 over wiseco pro lite pistons, FMF fatty pips and silencers, boost bottle, boysen reed pettles, K&N filter, vitto key, jetted stock carbs, plus2 durablue axle, 1.5 spacer for the front.. i have 35 mill keihin D slid carbs not installed yet... and soon to be head milled... i have 675 dollars invested into it!!! including the bike!!!

  10. #30
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    Jan 2011
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    Floyds Knobs, IN
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    Read through this whole thread and couldn't find any info about whats best for the type of riding you do. I was just wondering, but i race MX, and I have always been curious as to which cam is best for MX...Someone give me some info please. thanks Mods are in my signature.
    2004 Honda TRX450r
    Being built....

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